Some countries have their currencies fixed to other currencies. For example 1EUR is always 1.95583BGN (Bulgarian Lev). So when I pay in BGN, it’s nice to see that the exact rate is used and deducted from my base currency (EUR).
Other countries, example the UAE, have their Dirham fixed to the USD. 1USD is always AED3,6725. So when spending in AED I would want those amount taken from my USD-balance.
Several possible solutions:
1. Allow users to change the preferred currency (base currency) via user interface
2. Automatically deduct fixed currencies from their respective base currency
3. Allow users to determine which currencies should be deducted from which balance, possibly with a default list as per first point (this would, IMHO, be the best solution, as those who care can granually influence what happens, while other users find a meaningful solution without having to care)
In other words: It’s just silly to see AEDs taken from an EUR- or GBP-balance, if USDs are available.
PS - I don’t seem to be able to create an (un)-ordered list, hence the strange design of this post